Initially, the processing of mail involved a mailer dropping letters, or mail pieces, into a mailbox, having the post office pick up the mail from the mailbox, transporting the mail to a post office and dispatching the mail to its ultimate destination, whether this destination be local or out of town. As time progressed, large mailers would deliver the mail directly to the post office where the mail would be inspected, sorted and forwarded. The post office found that if the mailers were given postal discount rates for performing certain acts, such as the presorting of mail, bundling the mail, and the like, a great deal of time would be saved by the post office. As a result of such discounting, large mailers were encouraged to preprocess their mail and mail processing equipment such as scales, inserters, folders, and the like were developed to assist the mailer in his mailing operations. As a further development of streamlining mail processing, permit mail was created whereby the mailer was not required to place postage upon each mail piece, but rather was able to send the mail pieces to the post office in batch form. A statement sheet, such as a postal form 3602, would accompany the mail so that an accounting could be made for postage required for the mail.
Although what is outlined above worked fairly well for a period, the increase in amount of mail being processed by the post office became so large that the post office began experiencing delays in processing the mail. Presently, as much as 160 billion pieces of mail per day are being handled by the post office annually. This is placing a heavy burden on the post office with an attendant delay in the delivery of mail, as well as loss of postage due to inefficiencies in accounting due to the sheer volume.
As a result of the above problem, postal authorities held discussions with mailers and mail equipment manufacturers for the purpose of developing schemes that would be useful to the post office and allow the post office to process mail more quickly, efficiently and economically. As a result of these discussions, certain worksharing routines have been proposed whereby the mailer and certain mailing agents would perform tasks that would assist the post office in the processing and the delivery of mail. As an example, batch letter mail sent to the post office would be certified either by the mailer, or by a postal agent, whereby the certification of the mail assured the post office that the called for quantity of mail was accurate and that the postage being paid to the post office was sufficient. Another scheme involved certifying the deliverability of the mail. These schemes, and others like them, are still in the evaluation stage. Although these schemes have addressed many problems, there is one problem that is still in need of attention. This problem relates to the need of a postal clerk to make a fast determination with regard to the zip codes of stacked mail pieces and whether the number of mail pieces within a given zip code are sufficiently large in number for a postal discount.